Hybrid demonstrator



Nov. 10, 1964 A. L. HOLZMAN 3,156,092 Q3 f HYBRID DEMONSTRATOR L/f/Filed Aug. 9, 1962 INVENTOR: /JLzg/v #mz/MAN BYAMWM 7TH/@NETS UnitedStates Patent O 3,156,092 HYBRID DEMONSTRATGR Allen L. Holzman, PaloAlto, Calif., assignor to United Aircraft Corporation, a corporation ofDelaware Filed Aug. 9, 1962, Ser. No. 215,840 1 Claim. (Cl. 60-35.6)

This invention relates to a demonstration model of a hybrid motorutilizing a novel fuel and control system. The unit is small so that itis easily transportable and utilizes a safe combustion system operatingwith safe propellants. It is completely restartable due to itsselfcontained iginition system and the motor combustion can be viewedthrough the actual propellant fuel. It can be used as a laboratory toolfor the evaluation of chamber configuration, oxidizer flow rate, grainlength, grain composition and the like.

Generally speaking, the invention is carried out by providing a chamberof an oxidizable semi-transparent plastic such as Plexiglas(polymethylmethacrylate, also known as Lucite), polystyrene,polyethylene, Teflon, polybutyrate and the like. The plastic serves bothas the actual fuel during operation and also as a transparent chamber sothat one can watch the action of the hybrid motor. Plexiglas is idealfor this purpose since it serves as a typical hybrid fuel when used withoxygen, is clean-burning, and does not emit a carbonaceous exhaust.Further, it is a thermoplastic which is readily available as a moldingpowder as well as in rods and tubes, so that combustion chambers of anydesired configuration can be fabricated without diiculty. Since oxygenand plastics are not hypergolic, an electric ignition system, as Well asmeans for providing a hydrocarbon fuel for starting, form part of thehybrid unit.

In the drawings forming part of this application:

FIGURE l shows a hybrid motor in section embodying the presentinvention.

FIGURE 2 is a schematic diagram of the control circuitry used inconnection with the hybrid motor.

Referring now to the drawings by reference characters, there is shown inFIGURE 1 a hybrid motor generally designated 3 having a combustionchamber 5 fabricated of transparent plastic with a center burning port7. Although the port 7 has been shown as a straight tube, otherconfigurations might be used, such as an internal burning star and rodsof combustible material which might be suspended within the port. At oneend of the combustion zone, a nozzle 9, suitably of metal, is provided,while at the other end an ignition chamber 11, which may also be made ofmetal, is provided having a spark plug 13. An oxygen line 15 and apropane line 17 enter the ignition chamber 11 as is shown. An oxygentank 19 which may have a valve 21 and a pressure regulator 23 providesoxygen in line 25 through a solenoid valve, 27. Similarly, propane issupplied from a tank 29 through valve 31 to the propane solenoid valve33.

A suitable control circuit is shown in FIGURE 2, wherein the wires 35and 37 lead to a source of electricity "ice such as an ordinary voltA.C. outlet. The circuit is fused as at 39 and the wires lead to amomentary contact switch 41 and to the oxygen solenoid 27. The wiresalso lead to a time delay relay 43 of the type wherein the contacts 45and 47 remain closed only for a Short length of time, suitably 0.25 to0.50 second after the relay is energized, and then open. The circuitsformed by the wires 49 and 51 are thus energized only for a short lengthof time after current is first applied and during this short intervalthe propane control valve 33 and a step-up transformer 53 are activated.Suitable wires lead from the step-up transformer 53 to the spark plug13. Indicator lights as at 55, 57 and 59 can be employed.

To operate the device, it is only necessary to close the switch 41 forthe length of time for which it is desired to operate the motor. Theoxygen valve 27 will remain open for the entire length of time that theswitch 41 is closed, while the relay 43 will momentarily open thepropane valve 33 and actuate the spark coil 53 for a short period oftime to initiate burning. The propane and spark will then beautomatically turned off and the motor will then operate utilizing onlythe plastic as a fuel and will continue to operate until the switch 41is opened. The motor can be restarted any number of times merely byclosing the switch 41 until the plastic fuel is consumed, whereupon itcan be replaced and the operation started over.

Although propane has been given as a typical example of a suitablestarting fuel, other volatile fuels such as naturalgas, ethane, buanekorthe like can be used.

It is believdpparent from the foregoing that I have provided a safe yeteffective hybrid demonstration unit which can be used as a research toolin exploring hybrid engine parameters.

I claim:

A caseless hybrid rocket motor comprising a centrallyperforated,elongated propellant-grain of transparent, oxidizable plastic, saidgrain having sufficient web thickness to cause combustion to occurwithout rupture for a predetermined time, said grain having a forwardend and an aft end, a nozzle connected to the aft end of said grain,means for storing fluid oxidizer, and means connected to the forward endof said grain for injecting said fluid oxidizer onto the surface of thegrain perforation, said transparent grain serving to allow visualobservation of the combustion phenomenon.

References Cited by the Examiner UNITED STATES PATENTS 1,958,773 5/34Stuart 158-28 2,519,889 8/50 Crawford 158-28 2,632,294 3/53 Wall 60-35.62,771,741 ll/56 Barnard 60-3946 2,791,883 5/57 Moore et al. 60--35.62,990,682 7/61 Mullaney 60-35.6

SAMUEL LEVINE, Primary Examiner.

